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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ce88281b12afba30064fb2c72687e55c4eee1d2a1bf7954b5937e4c545ce530' 
  AND token = '+3JKHFp/Ux7m6CQdTlsSyQ1QQ7rdbl9TWN0Tlu1WY4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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