SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8b7f672ced41aa367a20f7426d3c43026bb91e5b52610c0a0b1843e65d89f4d' 
  AND token = 'kPKrnoSjOWKnppyljwk5g840w1Af60nN76E+JxHGs1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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