SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '424e195adf6165767b68db1cc45e009b08b0ac72869013d2c849844906f68c2e' 
  AND token = 'URzOezUjiEhywnzysXDYt33wCbI+GOwkGK3Lzd1PBHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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