SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ab8701dd8c55da0eba99dd01bef1c46b0b976d5df0e9794a11cf91674591fec' 
  AND token = 'JdAdbvEXJv5qIDdSO2i1dcE5EoCrGYryj3AcHG6g+Fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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