SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fb4c7354698a671e4318a2070c3fdacf1a15e9df0c8676db778a42a902879a1' 
  AND token = 'qjeLjMLbPypLyUFs+Jtd7BRSbKYKdUml7mZM1VNaSqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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