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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9db0c653f6c6155cd54e39038d62ac0b2224c69f14fcf3c30e2da1b44fbadf7' 
  AND token = 'c4peMTdOBZ1dSYz3R3RvGxgm0kd/dxqyUQA2pdAbNNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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