SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '278022a0a293e70467c11c87ef82ab539447d5e2e699164829066c746d525439' 
  AND token = 'uHSM7mNgwlgwgjl2xQP6LZkXrBJf5JwjkVFTTWqYQnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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