SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3de6930ee25669ecda125f0095440a8237e4daf059071518181a378e1464315' 
  AND token = 'xDClGeofDnXd/MCYVqbMhmZAF1Sm2D4/LHNGaInomyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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