SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15531444c944b94c1e57aece3152e21c4dc343e7a6dd25e2d8f0bbf36364f0eb' 
  AND token = 'rB5oqUofmoaGsE5wdJtqr3eOfLvfwFEYOOPpetrUzaA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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