SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c234e5b590f27243dba26381f3a8a318c10fd6d754dee7034a5780774f8251c' 
  AND token = 'VZ8GPkfYHcN2FytIGUMyrkSFknDUfG8oF+nii1TpwPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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