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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd51307fc85e921f1a13c59de07d97705df75e6fc5f7c7ddbd86a0ea4348eefc5' 
  AND token = '6fGF9DDWaDqFTYVULgTsUVD9MkKfU0SLnlCL4Y5xtNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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