SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75d46c980b540ec2b09521ea125c44c67b90841492ebb3370c8220dd70d24991' 
  AND token = 'f505EKmzbBGVUVitQ+oR4/Frcg4ClWaIACAkY2pRd3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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