SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38a400f85957a017262a25748ebc3c5b1aa68cc6b2b3b16c9459d316428b112e' 
  AND token = 'aKIpLRDKKHqfrIFNV4GVc1rcKydW98goMPUsqXwC7Sw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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