SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a90aa133d9508ab7e7ae667bdf10929dcc1b2192be6ff241728f3a7a2bdb3dc8' 
  AND token = 'H+d2IPHCpv5gRM/iwA/OqTYjqe3VmVA8z6e3COG2Syc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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