SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38a1591e1820746e6fe675cab744a2797b73d99016596cf4bcf39c95f04cfd68' 
  AND token = 'NvKtqST3K3XcuYF2tbks+zWQ7XBGn+Juaw9Iir6GKyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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