SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db2e27159bf34688e0a02124ce8d7a6f18c30f820fcb41b4a66104d5409e6869' 
  AND token = 'OS4fGPaM1tbI6Jt34MfaH481PcRKs4cN39ATeaVrEKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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