SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '784857b864fa883d1507a52238f82b65576a66110ee6442d04479dd2041e189d' 
  AND token = 'iPe3vA4lkpc/JfzKN2Azwbb9opMiXFvB1dVQwHS+QyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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