SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29fbc5a89343fd85cc5673a1166dfb1d20f88b9e90d29715a5936bf5a5a7859c' 
  AND token = '/aixlPeguUhlKxtLxjwizACUYwx7+SBfF3rSAst9x+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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