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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e92c9d6843bdedcdb7190c4644105a9430a0f413b4bcac6d453abe5038a8f334' 
  AND token = '/kNlTQSFnsA+SjuzGvNEFbBv7IQU5p20W80vFvL8ZVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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