SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f4a7153e06a78aecf23ce7a52bc9df1799993ae7f052cd3bd187bd51ade0b79' 
  AND token = 'DW9BCY+iC+LMcy9K0Xe7joYkEqyOeiiFdiK3GyfYN6I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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