SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f654da423f0eefe67ee3a017420166138966edb0274ee094d13877d28b1dd28c' 
  AND token = 'g3GrivxGqbi6nMl2I6zbBUW1Jrg3uCkRrTxrVz5tKS4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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