SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59eab5176f5fe20e1cac050189055e9591f0d5fff4b4d60a0facae476f31b90b' 
  AND token = 'e9PFqlAqCav7m7KJhAQFxebwzQJ+3jwdAGNLBrsMLm0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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