SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '854217075d3d2fefe446268ed865cfd91e44c0a20dc19d579519f5ac94cac912' 
  AND token = 'ut+QrDR5hP1n79iqXL85pTnwXOfmSnNt2iLtW9fWyb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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