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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d8420e1eb47dd08e5cf98680bf75105fb2ff6c2ea3a4eaf92f83b59d115e52b' 
  AND token = 'gF+40lOkJ40PesaoFQiCJPfhR/vkLfFDqC2UEGOT9xo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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