SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5226d7890b3416fd991a0d7b1601b4e687235abaacee6d2e26a017957243dcf' 
  AND token = 'DjH+I5rHefi7+lrhop4rg9vy0upzZy6rRtGAp2iJxuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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