SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd523dfe31d343fe3553bd61bed4b21b3da7befa21f7a7817e06c115ae9418105' 
  AND token = 'wHuEdIbiCrxLHqOoyhJRwrkSgrbpxwhSkrdu7HxerMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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