SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b358abecfcafebb0af2c9d5e87f3890ca63b42a63c0ebf0a7c7775db41bededc' 
  AND token = 'tHmepu+3GlVoZDsr61df9irabqjGxf9557VcOwGcczQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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