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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f834695683a0eb83d699a6eada3352d5f13f267bfd2a1fc43e0b90379a7cdc21' 
  AND token = '3vNjTWx1xiiO5ajqmRavcdeBcWjgBuZti4gAPUU9AkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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