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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74be55a6381ea6609aa8c522ad0c414c0f06e3865bf1d597bf0d6b4d47e83aa4' 
  AND token = 'hn4Q5dTsJLIfsFHTCNXOCVWVJCO8jEfNVnXTJ/BY1oo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}