SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b3247e2a355c10e2f3e87945a0955bd372909cd8cb586f6b898625a5ede2b2f' 
  AND token = 'zWTCbdzXNnJx/a2PjowwETnPko6/YlB8hZezKUGjT6k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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